The present invention relates to an optical pickup that is used for an optical disc device for reproducing or recording information on the recording surface of an optical disc.
An optical pickup is a device for focusing laser light onto the recording surface of an optical disc, and detecting the laser light reflected from the recording surface of the optical disc. The optical pickup is constituted from a combination of optical elements such as a laser light-source, a mirror, a lens, and an optical detector.
An optical element is fixed onto the housing of the optical pickup with the use of an adhesive agent. In the adhesive-agent-used fixing, unlike the screw-used fixing, there exists no necessity for providing a space where the screw-fastening portion is to be formed. Accordingly, the adhesive-agent-used fixing is suitable for the fixing of small components like the optical elements.
Because of a lapse of time and a change in environmental temperature, however, the adhesive agent is caused to give rise to the occurrence of phenomena such as its hardening, shrinking, and expansion. Moreover, these phenomena give rise to the occurrence of the position shift and angle shift of an optical element. If these shifts are caused to occur, an aberration is caused to occur on the spot of the laser light that is focused onto the recording surface of the optical disc. This occurrence of the aberration results in the occurrence of an inconvenience that it becomes difficult to perform the high-density recording. Consequently, in order to provide the high-reliability optical pickup, it becomes absolutely necessary to consider the following design and method: Namely, the design of an adhesion structure where the adhesive agent's characteristics are taken into consideration, and an adhesion method for implementing this adhesion structure with a high accuracy.
In JP-A-2004-220637, as a method for reducing the position shift of an optical element that is to be adhesively fixed, the disclosure has been made concerning the configuration that a wedge-form block and a guidance plane are used in the adhesion portion.